1. Field of the Invention
The present invention relates to a printing system, an image forming apparatus, a pull printing method, and a pull printing program. More particularly, the invention relates to a printing system including a printing server and an image forming apparatus for pull printing print data stored in the printing server, the image forming apparatus, a pull printing method executed at the image forming apparatus, and a pull printing program executed at the image forming apparatus.
2. Description of the Related Art
A known printing method generally referred to as pull printing involves storing printing data in a printing server and causing an image forming apparatus represented by an MFP (Multi Function Peripheral) to form an image of the printing data. In order to secure confidentiality, the pull printing has such a mechanism that the printing data is printed only from an instruction by a user authenticated at the printing server.
For example, Japanese Laid-Open Publication No. 2007-158867 describes an image processing apparatus wherein the image processing apparatus transmits user authentication information to a file server that in turn transmits the received user authentication information to an authentication server, and when the authentication server authenticates the information, the file server transmits image data to the image processing apparatus. However, the conventional image processing apparatus cannot receive image data unless user authentication information is transmitted to the file server. This creates the problem of having to input user authentication information every time image data is processed. In addition, the file server does not transmit the image data unless the authentication by the authentication server is successful, thereby creating the problem of necessitating an authentication by the authentication server every time the image processing apparatus makes a transmission demand of image data.
Japanese Laid-Open Publication No. 2007-245627 describes an image forming apparatus including: an authentication portion to authenticate a regular user; a ticket generating portion to generate a job execution ticket containing permission conditions upon which execution of a job is permitted; a data acquiring portion to output to a network-connected server device the job execution ticket and an acquisition demand of data selected by the regular user who has logged in after the authentication; and a control portion to, upon receipt of data attached with a job execution ticket within a predetermined elapse of time from log-out of the regular user, permit processing of the data in accordance with the above permission conditions even after the regular user has logged out. In receiving data from the server device, the image forming apparatus has to generate and transmit a job execution ticket, and further, retain the job execution ticket until receipt of data and, when receiving the data, compare the retained job execution ticket with a received one. This creates the problem of involving special processing for the generation, transmission, retention, and comparison of job execution ticket.